Method of washing a textile product

ABSTRACT

There is provided an excellent method of washing a textile product in a treating method using a treating apparatus of the type, such as a liquid current treatment apparatus that treats a textile product by circulating the treating liquid, which washing method is capable of completely or substantially completely removing oligomer, dyeing residues or the like and is unlikely to cause insufficient washing or excessive washing. A method of washing a textile product includes a high-temperature treating step of treating a textile product by loading the textile product in a treatment tank, and bringing a treating liquid circulating the inside and outside of the treatment tank into contact with the textile product while heating the treating liquid to a high temperature by an indirect heat exchanger disposed in a portion of a circulation passage of the treating liquid; and a liquid replacement washing step of gradually supplying a washing water into the treatment tank while gradually discharging the high-temperature treating liquid from the treatment tank, during which the high-temperature treating liquid to be discharged is directly heat exchanged with the washing water to be supplied, and lowering the liquid temperature within the treatment tank to a predetermined temperature while making the amount of the high-temperature treating liquid equal to the amount of the washing water to be supplied, thereby keeping the amount of liquid within the treatment tank constant, in which an optimum value of the temperature gradient in the liquid replacement washing step is previously set, so that the actual temperature gradient is brought at or close to the optimum value by heating or cooling the treating liquid by the indirect heat exchanger.

TECHNICAL FIELD

The present invention relates to a method of washing a textile product, such as a woven fabric, which is to be carried out subsequent to another treatment such as dyeing.

BACKGROUND ART

As an apparatus for carrying out a treatment such as dyeing for a textile product, for example, a liquid current treatment apparatus as illustrated in FIG. 4 is generally used. This apparatus has a retention part 2 for a textile product 1 such as a woven fabric, and an annular treatment tank 4 connected between the retention part 2 and a transfer passage 3 for the textile product 1. The retention part 2 has a bottom portion provided with treating liquid suction portions 5 (three in this Figure), through which a treating liquid is sucked. The sucked treating liquid is controlled to a given temperature (generally, a maximum temperature for it is set at a high temperature of 100° C. or higher) and returned to a treating liquid injection part 8 mounted at an end of the transfer passage 3 via a circulating pump 6 and an indirect heat exchanger 7, so that the textile product 1 is treated with a liquid current thereof, while being transferred.

In this liquid current treatment, the treating liquid has various dyes, other chemical agents or auxiliary agents remaining therein at the time when the treatment has been finished. In addition, it contains as products resulting from fiber polymerization, oligomer, shag and scale generated from the textile product 1.

Therefore, when carrying out, for example, polyester deep dyeing, a cooling water is introduced into the indirect heat exchanger 7 subsequent to the finish of the treatment, thereby lowering the temperature of the treating liquid, while circulating the treating liquid; and then once the treating liquid has been lowered to around 80° C., it is kept at this temperature, while hydrosulfite or an alkaline chemical (caustic soda, soda ash or the like) is injected into the treatment tank 4, thereby carrying out a reduction treatment for the aforesaid remaining products. Thus, a so-called reduction washing is carried out. Subsequent to this reduction washing, the treating liquid is again cooled to around 60° C. and discharged. Then, supplying a washing water (generally, water), water washing and discharging water are repeated several times, thereby washing the fabric product 1, and then the fabric product is taken out from the treatment tank 4. An example of a series of the aforesaid dyeing and washing steps is illustrated in FIG. 5.

However, as can be seen from an operation schedule of FIG. 5, the above washing method may pose problems of necessitating a long time washing, not realizing a smooth temperature gradient in cooling, causing wrinkles in the textile product 1, and thus likely deteriorating the quality of the fiber product 1. Also, since oligomer and the like, which have been dissolved at high temperature, are again precipitated, left in the treatment tank 4 and adhered thereto, a so-called tank washing is to be frequently carried out, which is very troublesome and thus poses a problem.

In order to deal with the above problems, the present applicant already proposed and put into practical use an all-new washing method that carries out a treatment by spraying a gas-liquid mixed fluid of a treating liquid and air current onto a textile product while moving and circulating the textile product within the treatment tank, which method involves discharging the treatment liquid at high temperature, and then supplying a washing water while heat exchanging with the discharged treating liquid (cf. Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-open No. Hei-8-269863)

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Accordingly, it is conceivable to apply the washing method in the above air current treatment apparatus to the liquid current treatment apparatus. However, it has been found that since the amount of a treating liquid used in the air current treatment apparatus is different from that of the liquid current treatment apparatus, and the structures of the apparatuses are different from each other, it is difficult to apply the aforesaid washing method to the liquid current treatment apparatus without modification.

Consequently, the present applicant has developed a washing method for a textile product that is capable of carrying out effective washing treatment in a shorter time even in a treatment method of a liquid current type that treats a textile product by the circulation of a treating liquid, and already filed an application (Patent Application No. 2004-295212).

FIG. 6 illustrates an example of the apparatus of the above application. The basic structure of this apparatus is similar to that of FIG. 4, and therefore the description thereof will be omitted by allocating the same reference numbers to the same parts or portions. This apparatus has a treating liquid circulation passage 10 provided with the aforesaid circulation pump 6 and indirect heat exchanger 7, a treating liquid discharge conduit 11 for taking out a part of the circulating treating liquid and discharging the same to the outside that is connected on the intake side of the circulation pump 6 to the treating liquid circulation passage 10, and a washing water supply conduit 12 for supplying a washing water into the treating liquid circulation passage 10 that is connected on the downstream side of the connection portion thereof via a check valve 13 to the treating liquid circulation passage 10. Both the treating liquid discharge conduit 11 and the washing water supply conduit 12 extend through the heat exchanger 14 so that a high-temperature treating liquid and a room-temperature washing water are directly heat exchanged with each other. Both the treating liquid discharge conduit 11 and the washing water supply conduit 12 are respectively provided with shut-off valves 15, 16 and fluid meters 17, 18, so that the amount of the treating liquid to be discharged is controlled to be equal to the amount of the washing water to be supplied. Reference numerals 19 and 20 respectively represent a washing-water supply pump and a feed valve.

The washing method of the above application is to treat and wash a textile product 1 by the use of the aforesaid liquid current treatment apparatus, for example, in the following manner. Specifically, in the same manner as a conventional liquid current treatment apparatus, the textile product 1 such as a woven fabric is first loaded into the treatment tank 4, and the treatment is made in the same manner as a regular treatment with the shut-off valves 15, 16 kept closed. Then, upon the finish of the treatment, the water supply valve 20 is opened, the pump 19 is started, and the shut-off valves 15, 16 are opened so that a part of the treating liquid circulating within the treating liquid circulation passage 10 is taken out into the treating liquid discharge conduit 11, and at the same time the washing water is supplied into the treating liquid circulation passage 10. At this moment, they are passed through the heat exchanger 14 so that heat exchanging is made between the high-temperature treating liquid to be discharged and the room-temperature washing water. In addition, the flow control is made by using the fluid meters 17, 18 and the shut-off valves 15, 16 so that the amount of the treating liquid to be discharged and the amount of the washing water to be supplied are controlled to be constantly equal to each other. Whereby, it is possible to carry out the washing while keeping the amount of liquid circulating within the treatment tank 4 (the mixed liquid of the treating liquid and the washing water, in which the treating liquid is gradually replaced with the washing water) constant. This washing step is called as a “liquid replacement washing step”.

As illustrated in the operation schedule of FIG. 7, at the time when the liquid temperature has dropped to a medium temperature range (80° C. in this example) which is higher than a low temperature range in which the liquid can be discharged, the shut-off valve 15 is closed to stop the taking-out of the high-temperature treating liquid from the treating liquid discharge conduit 11, and then the washing water is directly supplied into the treatment tank 4 at a constant feed rate without heat exchanging with the high temperature discharge liquid so as to cool the circulating liquid (direct cooling and washing). The washing water is not necessarily supplied at a constant feed rate in this operation, and the amount of the liquid increased in the treatment tank 4 by the supply of the washing water is gradually discharged through a drain valve. Then, at the time when the temperature of the circulating liquid has reached a predetermined low temperature range (60° C. in this example), the supply of the washing water is stopped, the textile product 1 is taken out and thus a series of the treatments is finished.

According to the above washing method, in the liquid replacement washing step, the high-temperature treating liquid used in the treatment is discharged while keeping the temperature thereof high, and at the same time it is heat exchanged with the room-temperature washing water to be supplied into the treatment tank 4. Thus, the temperature of the washing water becomes much higher than in the conventional method, thereby producing an excellent washing effect. Since the treating liquid is discharged while keeping the temperature thereof high, oligomer, dyeing residue or the like are kept dissolved in the treating liquid when discharged, a reduction washing treatment required in conventional polyester deep dyeing or the like can be omitted. Thus, steam or chemical agents used for increasing the temperature in the reduction cleaning treatment is not required, which contributes to the cost reduction. Since the amount of the oligomer or dyeing residue adhered to the inner wall or the like of the treatment tank and remaining in the treatment tank is decreased, there is an advantage in that the workload in maintenance such as cleaning the treatment tank 4 on regular basis is reduced. In addition, since the amount of the high-temperature treating liquid to be discharged is controlled to be equal to the amount of the washing water to be supplied, the amount of liquid circulating in the treatment tank 4 can be kept constant even when the process transfers from the dyeing or the like treatment to the washing treatment, and thus the textile product 1 is prevented from being subjected to excessive stress and is provided with a good finish.

Meanwhile, in the above washing method, the timing for the transfer from the liquid replacement washing step to the next step (e.g., the aforesaid direct cooling and washing step) is usually determined based on the temperature control, and specifically the liquid temperature within the treatment tank 4 is measured with time by a temperature sensor and when the measured temperature reaches a predetermined temperature (80° C. in the above example), the instruction for actuation is transmitted to an electromagnetic valve or the like of the apparatus, thereby allowing the operation to proceed to the next step.

However, when the timing for the transfer from the liquid replacement washing step to the next step is determined based on the temperature control, the finish time of the liquid replacement washing step may become early or late depending on the liquid temperature, and thus it has been found that poor washing or wasteful consumption of water due to excessive washing is caused. For example, when the amount of the washing water to be supplied is set to enable the washing water to achieve satisfactory washing in 20 minutes in the above liquid replacement washing step, on the condition that the temperature of the washing water to be supplied into the treatment tank is a normal temperature (18-20° C.) and it takes 20 minutes for the liquid temperature within the treatment tank to reach 80° C., the temperature gradient caused by the liquid replacement becomes large when the water is cold in the winter, therefore the temperature of 80° C. is reached, for example, in 15 minutes, causing the operation to proceed to the next step. As a result, the amount of the washing water required for washing becomes insufficient and insufficient washing is encountered. On the contrary, when the water is warm in summer, the temperature gradient caused by the liquid replacement becomes small, and therefore the temperature of 80° C. is reached, for example, in 25 minutes, so that the washing water is excessively supplied and thus is likely to be wastefully consumed.

The present invention has been conceived in consideration of the above circumstances. It is an object of the present invention to provide an excellent method of washing a textile product in a treating method using a treating apparatus of the type, such as a liquid current treatment apparatus that treats a textile product by circulating the treating liquid, which washing method is capable of completely or substantially completely removing oligomer, dyeing residues or the like and is unlikely to cause insufficient washing or excessive washing.

Means for Solving the Problems

In order to achieve the above object, there is provided a method of washing a textile product, which includes a high-temperature treating step of treating a textile product by loading the textile product in a treatment tank, and bringing a treating liquid circulating the inside and outside of the treatment tank into contact with the textile product while heating the treating liquid to a high temperature by an indirect heat exchanger disposed in a portion of a circulation passage of the treating liquid; and a liquid replacement washing step of gradually supplying a washing water into the treatment tank while gradually discharging the high-temperature treating liquid from the treatment tank, during which the high-temperature treating liquid to be discharged is directly heat exchanged with the washing water to be supplied, and lowering the liquid temperature within the treatment tank to a predetermined temperature while making the amount of the high-temperature treating liquid to be discharged equal to the amount of the washing water to be supplied, thereby keeping the amount of liquid within the treatment tank constant, in which an optimum value of the temperature gradient in the liquid replacement washing step is previously set, so that when the actual temperature gradient is larger than the optimum value, the treating liquid is heated by the indirect heat exchanger, and when the actual temperature gradient is smaller than the optimum value, the treating liquid is cooled by the indirect heat exchanger, thereby bringing the actual temperature gradient at or close to the optimum value.

ADVANTAGES OF THE INVENTION

Specifically, according to the textile product washing method of the present invention, in the liquid replacement washing step in which the high-temperature treating liquid used for the treatment is discharged while being heat exchanged with the washing water supplied into the treatment tank, the temperature gradient caused by the heat exchange between the high-temperature treating liquid and the washing water is controlled to be brought at the previously set optimum value. Whereby, the time required for finishing the liquid replacement washing step becomes constant regardless of whether the temperature of the washing liquid to be supplied is high or low, and therefore it is unlikely that the time for finishing the treatment is shortened, thereby causing insufficient washing, or the time for finishing the treatment is elongated, thereby causing excessive supply of the washing water and hence inviting wasteful consumption. Since the treating liquid is discharged while maintaining high temperature thereof and it is gradually replaced with the washing water, oligomer or dyeing residues or the like kept dissolved in the treating liquid at a high temperature can be removed while preventing them from being separated out into the liquid, and hence a reduction washing treatment required in a conventional polyester deep dyeing or the like can be omitted. Since cooling and washing can be simultaneously carried out while supplying the washing liquid with oligomer or the like removed, it is not necessary to repeat the washing after that, and it is possible to finish the washing treatment in a short time. Since impurities such as oligomer are unlikely to be adhered to the inside of the treatment tank and left therein, there is an advantage in that it is possible to greatly reduce the workload in maintenance such as cleaning the treatment tank on regular basis.

Moreover, likewise to the invention of the aforesaid prior application (patent application number 2004-295212), the amount of the high-temperature treating liquid t to be discharged and the amount of the washing water to be supplied are controlled to be equal to each other. Thus, the amount of the liquid circulating within the treatment tank is kept constant even when the process transfers from the dyeing or the like treatment to the washing treatment, and thus the textile product is prevented from being subjected to excessive stress and is provided with a good finish.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an operational schedule according to one embodiment of the present invention.

FIG. 2 illustrates a partial operational schedule in another embodiment of the present invention.

FIG. 3 is a partial operational schedule in still another embodiment of the present invention.

FIG. 4 is an explanatory view for illustrating a conventional treatment apparatus.

FIG. 5 illustrates a conventional example of the operational schedule.

FIG. 6 is an explanatory view for illustrating a treatment apparatus of the aforesaid prior application.

FIG. 7 illustrates an operational schedule in one example of the aforesaid in prior application.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the description will be made for a best mode for carrying out the present invention.

A washing method of the present invention is to wash a textile product 1 in the following manner by using, for example, an apparatus as illustrated in FIG. 6. The structure of the apparatus is as described above and thus its explanation will be omitted. Specifically, in the same manner as a conventional liquid current treatment apparatus, the textile product 1 such as a woven fabric is loaded into the treatment tank 4, and the same treatment is made with the shut-off valves 15, 16 kept closed. Then, at the time when the treatment has been finished, the feed valve 20 is opened, the pump 19 is actuated and the shut-off valves 15, 16 are opened. Whereby, a part of a treating liquid circulating within the treating liquid circulation passage 10 is taken out into the treating liquid discharge conduit 11 and at the same time the washing water is supplied into the treating liquid circulation passage 10.

At this moment, the high-temperature treating liquid to be discharged and the room-temperature washing water are heat exchanged with each other by bringing them through the heat exchanger 14. Then, the feed rate control is carried out by using the fluid meters 17, 18 and the shut-off valves 15, 16 to allow the amount of the treating liquid to be discharged to be constantly equal to the amount of the washing water to be supplied. Whereby, the washing can be carried out while keeping constant the liquid amount and liquid temperature, of the liquid (a mixed liquid of the washing water and the treating liquid, in which the treating liquid is gradually replaced with the washing water) circulating within the treatment tank 4.

Then, the circulating liquid is completely replaced with the washing liquid, and at the time when the liquid temperature within the treatment tank 4 has reached 80° C., the shut-off valve 15 is closed to stop taking out of the high-temperature treating liquid from the treating liquid discharge conduit 11, and the washing water is directly supplied into the treatment tank 4 at a constant feed rate without heat exchanging with the high-temperature discharged liquid, thereby cooling the circulating liquid (direct cooling and washing). At this moment, it is not necessary to supply the washing water at a constant feed rate, but the amount of the liquid increased in the treatment tank 4 by the supply of the washing water is gradually discharged through a drain valve. Then, at the time when the temperature of the circulating liquid has reached a predetermined low temperature range (60° C. in this example), and if necessary, the liquid is directly discharged through a drain port (not illustrated) provided in a portion of the treating liquid circulation passage 10. The textile product 1 is taken out and thus a series of the treatments is finished.

In the above washing method, a series of the operation controls is carried out by previously inputting and setting the values required for the operation controls into a predetermined control panel (not illustrated) provided in this washing apparatus. At this time, the timing, at which the process transfers from the liquid replacement washing step, in which the discharge of the high-temperature treating liquid and the supply of the room-temperature washing water are carried out while they are directly heat exchanged with each other, to the next step (the direct cooling and washing step), is set to be determined by detecting the time, at which the liquid temperature within the treatment tank 4 has reached 80° C., by a temperature sensor.

In the liquid replacement washing step, the optimum value of the temperature gradient in the temperature drop due to the liquid replacement is also previously input into the control panel. As the “optimum value of the temperature gradient”, for example, three values X, Y and Z may be input, which are set, in which it takes Z=20 minutes for the temperature to drop from the temperature (X=130° C.) at the time of the finish of the dyeing treatment to the temperature (Y=80° C.) at the time of the finish of the liquid replacement washing step, or a numerical value representative of the drop in temperature per unit time: (130° C.·80° C.)/1200 sec.=0.04° C./sec. may be input.

In FIG. 1, as illustrated in broken line A, when the actual temperature gradient is larger than the optimum value, and specifically when the liquid temperature of the washing water supplied into the treatment tank 4 is excessively low and hence the liquid temperature within the treatment tank 4 is sharply lowered, an instruction is made to heat the liquid within the treatment tank 4 by using the indirect heat exchanger 7 provided in a portion of the treating liquid circulation passage 10, and thus the temperature gradient is minimized by this heating and is brought at or close to the optimum value. In FIG. 1, as illustrated in alternate long and short dash line, when the actual temperature gradient is smaller than the optimum value, and specifically when the liquid temperature of the washing water supplied into the treatment tank 4 is excessively high and hence the liquid temperature within the treatment tank 4 is not satisfactorily lowered, an instruction is made to introduce a cooling medium into the indirect heat exchanger 7 to cool the liquid within the treatment tank 4, and thus the temperature gradient is maximized by this cooling and is brought at or close to the optimum value.

By this temperature-gradient control, the time required for finishing the liquid replacement washing step becomes constant regardless of whether the temperature of the washing liquid to be supplied is high or low, and therefore it is unlikely that the time for finishing the treatment is shortened, thereby causing insufficient washing, or the time for finishing the treatment is elongated, thereby causing excessive supply of the washing water and hence inviting wasteful consumption. This is the most significant characteristic of the present invention.

In addition, according to the aforesaid washing method, since the high-temperature treating liquid to be discharged and the washing water to be supplied are directly heat exchanged with each other and the treating liquid is discharged while keeping its temperature high, oligomer or dyeing residues or the like can be removed while keeping them dissolved in the treating liquid, and hence a reduction washing treatment required in a conventional polyester deep dyeing or the like can be omitted. Thus, steam or chemical agent for use in increasing the temperature in the reduction washing treatment becomes unnecessary, the cost reduction can be accomplished. Also, since the aforesaid oligomer or dyeing residue is unlikely to be adhered to the inner wall or the like of the treatment tank 4 and to be left therein, there is an advantage in that the workload in maintenance such as cleaning the treatment tank 4 on regular basis is greatly reduced. In addition, since control is made so that the amount of the high-temperature treating liquid to be discharged becomes equal to the amount of the washing water to be supplied, the amount of the liquid circulating within the treatment tank 4 is kept constant even when the process transfers from the dyeing or the like treatment to the washing treatment and thus the textile product is provided with a good finish.

In the present invention, by the “high-temperature treating liquid” is meant a liquid heated by the indirect heat exchanger 7 and thus having a temperature higher than the liquid temperature at the time of the supply. This temperature is appropriately determined according to the kind of the treatment, the kind of the textile product 1 or the like.

In the present invention, the “washing water” used has a lower temperature than the high-temperature treating liquid to such an extent as to enable itself to lower the liquid temperature of the high-temperature treating liquid by the heat exchanging with the high-temperature treating liquid. However, this temperature is not necessarily limited to a specific temperature, and usually, city water is used without processing. It is also possible to use water with appropriate chemicals added thereto, aiming at improving washing effect, or giving a specific texture or function.

In the present invention, in order to keep the amount of liquid within the treatment tank 4 constant by allowing the amount of the high-temperature treating liquid to be discharged to be equal to the amount of the washing water to be supplied, it is not necessary to limit to the aforesaid method, in which the fluid meters 17, 18 and the shut-off valves 15, 16 are used to control the feed rates of both the treating liquid and the washing water, but another appropriate method may be used. It is conceivable that a level sensor is provided within the treatment tank 4 and the shut-off valves 15, 16 are controlled to keep the liquid level constant. However, since the treating liquid circulates within the treatment tank 4 with ripples in a liquid current treatment apparatus, it is difficult to determine the liquid level. Therefore, as described in the above example, the control made by the combination of the fluid meters 17, 18 and the shut-off valves 15, 16 is appropriate.

In the liquid replacement washing step, in which the discharge of the high-temperature treating liquid and the supply of the washing water are simultaneously carried out, for example, as schematically illustrated in FIG. 2, it is possible to, for example, carry out heating by the indirect heat exchanger 7 for a predetermined time from the start, thereby keeping the liquid temperature equal to the high temperature at the dyeing treatment (this step is called as a “constant-temperature washing step”), and then stop heating while carrying out only the washing by the high-temperature discharged liquid. With this method, the temperature at the time of washing is further increased and therefore more excellent washing effect can be obtained. Then, since the treating liquid is discharged while its temperature is kept high, oligomer, dyeing residue or the like can be completely removed while they are kept dissolved in the treating liquid, and hence it is possible to greatly reduce the workload in maintenance of the treatment tank 4.

Based on the same concept mentioned above, for example, as schematically illustrated in FIG. 3, a constant-temperature washing step may be carried out by first carrying out only the discharge of the high-temperature treating liquid and the supply of the washing liquid without heating by the indirect heat exchanger 7 after the dyeing treatment step, and lowering the liquid temperature within the treatment tank 4 to a slightly lower temperature such as in a range of 100-120° C. by the direct heat exchanging between both the liquids, at which heating by the indirect heat exchanger 7 is started. That is, the constant-temperature washing step is carried out with the liquid temperature lowered to an appropriate temperature to such an extent as not to cause impurities such as oligomer from separating out. Whereby, it is possible to further reduce the energy cost.

Thus, the liquid temperature in the liquid replacement washing step may be appropriately controlled according to the kind of a product to be washed, treating conditions or chemicals to be used. As a method of lowering the liquid temperature, it is possible to select a method such as by carrying out the discharge of the high-temperature treating liquid and the supply of the washing water while carrying out the direct heat exchanging, or a method using the indirect heat exchanger 7. In any case, it is essential to control the temperature gradient to be brought at or close to the optimum value in order to prevent the time required for finishing the liquid replacement washing step from being influenced by the fluctuation in liquid temperature of the washing water.

In the above example, the direct cooling and washing method is employed, in which the shut-off valve 15 is closed at the time when the liquid temperature has been lowered to 80° C., thereby stopping taking-out of the high-temperature treating liquid from the treating liquid discharge conduit 11, and supplying the washing water directly into the treatment tank 4 at a constant feed rate without heat-exchanging with the high-temperature discharging water, aiming at cooling the circulating liquid. It is not necessary to employ this method, but it is possible to lower the liquid temperature to a low temperature range of 60° C. by only carrying out the washing with the high-temperature discharged water. However, according to the aforesaid direct cooling and washing method, it is possible not only to lower the liquid temperature to a predetermined low temperature range in a shorter time, but also to carry out the washing simultaneously with cooling because of the direct supply of the washing water into the treatment tank 4. Thus, the washing efficiency can be further increased. According to a conventional method, it is difficult to lower the liquid temperature at a smooth temperature gradient when lowering it to a low temperature range, the textile product 1 is easy to be wrinkled. By using the above method, there are advantages in that it is possible to achieve a smooth temperature gradient and wrinkles are unlikely to arise. Therefore, it is preferable to employ this method.

In the present invention, it is not necessary to limit a textile product to be treated to a specific type, but for example, various synthetic fabrics such as polyester, polyamide, acryl or the like fabric, their blended yarn fabric, combined weave fabric or blended knit fabric, or cellulose based fabrics such as cotton fabric, rayon fabric and hemp fabric, their blended yarn fabric, combined weave fabric or blended knit fabric. Any shape of the textile product, or any form such as weaved cloth, knitted cloth, nonwoven cloth or a product (garment) may be used as well.

In the present invention, as the aforesaid apparatus for treating a textile product and carrying out the washing, it is possible to use any type as long as it carries out the treatment by a treating liquid circulating inside and outside of the treatment tank. For example, in addition to the liquid current treatment apparatus as mentioned in the above example, it is possible to use various types of the treatment apparatus, such as a packaging apparatus that treats a filiform textile product by packaging the same into a skein form, cheese form or corn form, a beam treatment apparatus, or a treatment apparatus that treats a textile product formed by such as thread or weaved yarn, or extends the same into a flat shape by a suspension system, then forming it into a laminate, and then treats the textile product in this laminate form. Furthermore, they can be also applied to the air current treatment apparatus.

In the present invention, as the treatment to a textile product, in addition to the dyeing treatment, it is widely applied to various processes, such as a relaxation process, a resin process, a refinery process and the like.

Now, the description will be made for an example along with a comparative example.

EXAMPLE Example 1

The dyeing and washing of a textile product was carried out following the conditions mentioned below by using a liquid current treatment apparatus as illustrated in FIG. 6.

Textile product: polyester woven fabric (plain fabric of polyester yarn 56 dtex/48 f) 100 kg

Progress schedule: following FIG. 1, in which a temperature gradient enabling the liquid temperature to drop from 130° C. to 60° C. in 20 minutes in the liquid replacement washing step is designated as an optimum value, and when the temperature gradient is larger than the optimum value, the heating is carried out by the indirect heat exchanger 7, and when the temperature gradient is smaller than the optimum value, the cooling is carried out by the indirect heat exchanger 7 as well, thereby bringing the actual temperature gradient at or close to the optimum value.

Chemical agents used in the dyeing step:

-   -   Dye compound: 5 kg     -   Dispersing agent (Nicca Sunsalt RM-340, made by Nicca Chemical         Co., Ltd.): 600 g     -   Acetic acid: 600 g

Liquor-goods ratio: 1/12

Liquid temperature of washing water and cooling water: two different temperatures of 15° C. and 28° C.

Comparative Example 1

Control was not carried out for the temperature gradient. Except for that, the dyeing and washing of a textile product was carried out in the same manner as Example 1.

Comparative Example 2

The dyeing and washing of a textile product was carried out following the conditions mentioned below by using a conventional liquid current treatment apparatus as illustrated in FIG. 4.

-   -   Textile product: same as that of the Example

Progress schedule: following FIG. 5

Chemical agents used in the dyeing step: same as those of the Example

Chemical agents used in a reduction washing step:

-   -   NaOH: 1200 g     -   Hydrosulfite: 1200 g

Liquor-goods ratio: Same as that of the Example

Upon checking the amount of each of steam, water (washing water, cooling water and the like) used in Example 1 and Comparative Examples 1 and 2, they were summarized in the following Tables 1 to 3, respectively. Evaluation was carried out for each of the obtained textile products in terms of various fastness, namely color fastness to rubbing (according to JIS L-0849 (dry/wet)), color fastness to washing (according to JIS L-0844 A-4) and color fastness to perspiration (according to JIS L-0848 A (Acid and Alkali)), and which grade from 1 to 5 each result falls in is indicated.

TABLE 1 Example 1 Water Temperature: Water Temperature: 15° C. 28° C. Amount Amount Items Steps Used Total A Used Total B Steam (kg) Heating 264.6 334.6 264.6 284.6 Kept at 130° C. 20.0 20.0 Temperature 50.0 — Gradient Correction Water (liter) Temperature Drop 4823 6023 4823 7023 (Washing Water) Temperature — 1000 Gradient Correction (Cooling Water)) Dyeing Process 1200 1200 (Water Supply) Slow Cooling 0 0 (Washing Water) Water Washing 0 0 (Washing Water) Power (kw) All the Steps 25.8 25.8 25.8 25.8 Dye Dyeing Process 5000 5000 5000 5000 Compound (g) Auxiliary RM340 Same as 600 Cost: 600 Cost: Agents (g) the Above JPY555 JPY555 Acetic Acid Same as 600 600 the Above Reducing NaOH Reduction 0 0 Agents (g) Washing Hydrosulfite Same as 0 0 the Above Fastnesses of Textile Product Good Good (Grades 4-5) (Grades 4-5)

TABLE 2 Comparative Example 1 Water Temperature: Water Temperature: 15° C. 28° C. Amount Amount Items Steps Used Total C Used Total D Steam (kg) Heating 264.6 284.6 264.6 284.6 Kept at 130° C. 20.0 20.0 Temperature Gradient — — Correction Water (liter) Temperature Drop 3000 4200 7000 8200 (Washing Water) Temperature Gradient — Correction (Cooling Water) Dyeing Process 1200 1200 (Water Supply) Slow Cooling 0 0 (Washing Water) Water Washing 0 0 (Washing Water) Power (kw) All the Steps 25.8 25.8 25.8 25.8 Dye Dyeing Process 5000 5000 5000 5000 Compound (g) Auxiliary RM340 Same as 600 Cost: 600 Cost: Agents (g) the Above JPY555 JPY555 Acetic Acid Same as 600 600 the Above Reducing NaOH Reduction 0 0 Agents (g) Washing Hydrosulfite Same as 0 0 the Above Fastnesses of Textile Product Insufficient Good Treatment (Grades 4-5) (Grades 3-4)

TABLE 3 Comparative Example 2 Amount Items Steps Used Total C Steam (kg) Heating 264.6 292.5 Kept at 130° C. 20.0 Kept at 80° C. 7.9 Water (liter) Temperature Drop 3818 17268 (Cooling Water) Dyeing Process (Water 1200 Supply) Slow Cooling (Washing 2500 Water) Water Washing 9750 (Washing Water) Power (kw) All the Steps 29.0 29.0 Dye Dyeing Process 5000 5000 Compound (g) Auxiliary RM340 Same as 600 Cost: Agents (g) the Above JPY 1053 Acetic Acid Same as 600 the Above Reducing NaOH Reduction 1200 Agents (g) Washing Hydrosulfite Same as 1200 the Above Fastnesses of Textile Product Good (Grades 4-5)

From the above results, it is found that washing is appropriately carried out even at 15° C. and 28° C., and a textile product having fastnesses equivalent to those of a conventional product (product of Comparative Example 2) is obtained in Example 1. On the other hand, in Comparative Example 1 in which the temperature gradient is not appropriately controlled, when the washing water has a temperature of 15° C., the time for which the liquid replacement washing step is maintained is short, thus the washing treatment is insufficient and the fastnesses of the obtained textile product are not good, and when the washing water has a temperature of 28° C., washing is excessively carried out in the liquid replacement washing treatment and thus the cooling water is excessively used.

As compared with Comparative Example 2, which is a conventional washing method, Example 1 can greatly reduce the amount of each of steam (except for the case where the water temperature is 15° C.), water, power and chemical agents, and the time required for the washing treatment is greatly shortened. Therefore, the cost can be greatly reduced. 

1. A method of washing a textile product, which comprises a high-temperature treating step of treating a textile product by loading the textile product in a treatment tank, and bringing a treating liquid circulating the inside and outside of the treatment tank into contact with the textile product while heating the treating liquid to a high temperature by an indirect heat exchanger disposed in a portion of a circulation passage of the treating liquid; and a liquid replacement washing step of gradually supplying a washing water into the treatment tank while gradually discharging the high-temperature treating liquid from the treatment tank, during which the high-temperature treating liquid to be discharged is directly heat exchanged with the washing water to be supplied, and lowering the liquid temperature within the treatment tank to a predetermined temperature while making the amount of the high temperature treating liquid to be discharged equal to the amount of the washing water to be supplied, thereby keeping the amount of liquid within the treatment tank constant, in which an optimum value of the temperature gradient in the liquid replacement washing step is previously set, so that when the actual temperature gradient is larger than the optimum value, the treating liquid is heated by the indirect heat exchanger, and when the actual temperature gradient is smaller than the optimum value, the treating liquid is cooled by the indirect heat exchanger, thereby bringing the actual temperature gradient at or close to the optimum value. 